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Discussion Starter · #1 ·
Hey everyone,

I just realized this month that I need new tabs for my subie and in order to do that I need to pass an emissions test. I pulled out my OBDII code reader so I could figure out if I would pass.

Well, it threw me two codes; one I managed to solve by replacing my O2 sensor, but this other one (p0400) is a little more difficult. I have already been pouring over the numerous posts on this site pertaining to this trouble code, but I had a few questions that I was hoping someone could answer.

First, I took off my EGR valve and gave it a good scraping. When I put it back on though, I realized that I don't really know what the "stem" part of the EGR valve is. The Haynes manual says it should move when the engine is reved but I would need to know what to look at before I can test it.

Also, assuming my EGR valve IS dead, is it a cheap replacement? I'm assuming I just need to order a new one and a gasket to go along with it?

The other thing I've noticed that people had to replace is the BPT. It looks like this might be an easy replacement as well.

I just don't want to fail the emissions test. If I fail I have to get a waiver and pay a certified mechanic at least 150$ in repairs. I'm assuming for that amount of money I could do at least twice the repairs that they would do for me.

I'm still learning so any help would be greatly appreciated.
 

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2014 OBW 3.6R Limited, 1997 OBW 2.5L Auto (sold, but not forgotten), and 1991 Ford F150
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If you can manually move the valve, then you know the cleaning was successful. If the bellows is intact, the EGR valve should then open when a vacuum is applied to it. Attach a small length of hose to the vacuum port on the valve and suck on it ... if the valve moves, then the EGR is good.

Also, assuming my EGR valve IS dead, is it a cheap replacement? I'm assuming I just need to order a new one and a gasket to go along with it?
Yes, if it is bad, just get a new one and bolt it on. List price for a new OEM EGR is about $190 ... online discount prices about $140 + shipping. Aftermarket ones run $130+, so it's hardly worth it. Go OEM.

I would never pay a mechanic for a P0400 as it can take a good deal of diagnosis ... something which most mechanics don't want to do. Instead, they'll just throw your money at it until they get lucky and replace the right part.

What year is your car?
 

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Discussion Starter · #3 ·
Its a 1997 Outback (technically a legacy I think).

Thanks for the testing tips, but what is the stem? Is it that little metal rod that runs through the EGR valve into the diaphragm?

The trouble for me, as it seems to be for everyone with this problem, is that there are multiple fail points that could need fixing right? I've also read that the BPT is a common EGR fail but there is no test for that.

But yes, I'd just rather spend the money and do it all myself than to have some mechanic tell me what COULD be wrong for 150$. Although there are multiple fail points, they all seem fairly simple repair wise.
 

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Discussion Starter · #4 ·
Just a quick update.

I checked the diaphragm / vaccum on the EGR valve by taking it off , pushing in the diaphragm and then plugging the hole where the tube connects, and the vacuum held. I'm assuming this means that the problem isn't in my EGR valve? Or at least that the EGR diaphragm itself is in good shape?

If anyone has any ideas on where I could go from here that would be awesome.

Thanks!
 

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i had an automatic once where i replaced the EGR, gasket, and solenoid to no avail. i finally replaced that small round quarter sized white with a gray foam filter like material around it on the passengers side vacuum hoses. it was like $7 or something from Subaru. code gone, car shifted smoother (it was hesitating downshifting up hills). 97 Impreza Outback. can't say i've ever seen anyone else have that problem though so i highly doubt that's it and i have no idea why that thing affected anything. my friends brother in law is still driving that car and no more issues many years and miles later.
 

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Discussion Starter · #6 ·
Wow. My car hesitates/slips when shifting too

Actually , you know, I checked that thing because I saw on other threads that it could be the problem. If it is only 7$ then I might just order one and replace it. Even if it doesn't clear the code, the filter that was there had no foam left on it. Is the foam supposed to go all the way around the disc?
 

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Thanks for the testing tips, but what is the stem? Is it that little metal rod that runs through the EGR valve into the diaphragm?
Yes, but it sounds like you already figured that out.
Is the foam supposed to go all the way around the disc?
Yes. The filter mentioned is:
22663AA010 Pressure Sensor Filter, list price about $11
photo:


The EGR solenoid valve is pretty easy to test, though you will probably have to remove it from the intake manifold to do so. Briefly apply 12 volts to the electrical pins and you should hear a (faint) click. If so, it is OK electrically. Blow through the valve ... if air passes through with 12v applied and does not pass through with no voltage, the valve is OK mechanically. If it fails either the electrical or mechanical test, replace it.

14774AA500 EGR SOLENOID VALVE, list price $106.

If EGR valve and EGR solenoid valve test OK and you've already replaced the Pressure Sensor Filter, you probably need to replace the BPT.

14741AA020 Back Pressure Transducer, list price $78.
 

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Discussion Starter · #8 ·
Rob,

Thank you for the detailed picture on the filter. I'll definitely get a new one as mine looks horrid compared to your picture.

I do still have some questions if you don't mind clearing some things up...

Where is the EGR Solenoid Valve? You said its in the intake manifold but I don't really know where that is, as I said before I'm still learning.

And and how do I apply the voltage you specified? I'm assuming there is some sort of tool I can find at an auto parts store for that?
 

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Where is the EGR Solenoid Valve?
It's on the other end of the vacuum hose that attaches to the EGR valve. Follow the hose back to the intake manifold. The solenoid has one bolt that mounts it to the IM ... 12mm IIRC. On my car, in order to remove it, I had to loosen the IM mounting bolts and lift the IM about a 1/2". If you have a thin-wall socket, you may not have to do this.

And and how do I apply the voltage you specified?
I used jumper cables with a nail or screw in the clamp. After disconnecting the solenoid, look at the wiring harness to determine which pin is positive/negative (red wire positive?).

EGR system photo:


Closeup of EGR Solenoid Valve:
 

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Discussion Starter · #10 ·
Awesome!

Funny enough when I was taking off the EGR Valve I think I traced one of those tubes to the Solenoid without even knowing.

This will really help me narrow down what I need to replace. Thanks again for the clear photos and labeling.

I'll tackle the Solenoid tomorrow and try not to fry myself with the jumper cables. :)

Oh and by the way, does the EGR system usually effect gas mileage in any way?
 

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Discussion Starter · #12 ·
Okay.

I got the EGR Solenoid off , luckily I didn't need to loosen the IM bolts like you said.

So now I need to spark the plug in points with my jumper cables hooked up to my car battery?

How am I supposed to tell which pin is negative and which is positive just by the wire harness?

One thing that was odd though is the when I was taking the tubes off ,the one that connects to the BPT through a metal hard line, some water came out of the tube and brought some pretty nasty black stuff with it. Is this normal?

Sorry if I'm asking too many questions but I just don't want to mess anything up!
 

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Discussion Starter · #13 ·
Update:

Applied suction to all the hoses of the EGR system that I could find. All of them seemed to be holding a vacuum. I couldn't get the EGR valve to move though. Granted I was just using my mouth to test, but I should have been able to get it moving right?
 

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You have to suck pretty hard (or use a pump). On my '98 I found one of the hard lines plugged with gunk. Once I cleared that out, the light went out on its own on the first highway trip.
 

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Discussion Starter · #15 ·
Okay. I think I might just buy a vacuum gauge pump at the auto parts store. If you don't mind me asking, was it the hard line under the EGR Vavle? That long thick one that seems to go under the car almost?
 

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EGR Solenoid Valve polarity from the 97 factory service manual:


The connector has green and yellow wires. It's been to long for me to remember for sure, but I THINK the yellow is the positive. Hopefully you can figure it out from the diagram above.

One thing that was odd though is the when I was taking the tubes off ,the one that connects to the BPT through a metal hard line, some water came out of the tube and brought some pretty nasty black stuff with it. Is this normal?
No, that is not normal. I'd take it as an indicator that the BPT is bad.

Applied suction to all the hoses of the EGR system that I could find. All of them seemed to be holding a vacuum. I couldn't get the EGR valve to move though. Granted I was just using my mouth to test, but I should have been able to get it moving right?
Again, it's been too long for me to remember for sure, but I believe I was able to move the valve with my own suction ... I used to be an opera singer, though, so my breathing and lungs are pretty strong-LOL. YMMV.
 

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Discussion Starter · #17 ·
Rob ,

I am by no means an opera singer! :)

I had to go ahead and test the thing without your advice though and I think I might have done it the other way around. I didn't hear any click , accept for the electricity , so I tried it the other way around and had no luck. I blew air through the thing and it didn't go through , but I still had no idea whether I was activating it or not when I applied the cables.

I think I may just buy a BPT, an EGR solenoid , and that little pressure filter. I've found some pretty good prices and can get all of that for under 150$.

In the meantime do you have any recommendations for testing that thick hard line that lies directly underneath the EGR valve? I can definitely get to the top bolt but how I would get to the bottom one I have no clue.
 

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If there is no click, then the solenoid is bad, so yes, you need a new one.

In the meantime do you have any recommendations for testing that thick hard line that lies directly underneath the EGR valve? I can definitely get to the top bolt but how I would get to the bottom one I have no clue.
That thick tube below the EGR is called ... the EGR tube. LOL. Getting the bottom bolt out is all but impossible with the engine in the car, so I would leave it alone.

You can remove the top bolt, then gently pry the tube away from the intake manifold and move it to the side to see if the port is clogged. Clean it out if it is. It's unusual for that tube itself to get clogged. You could try fishing a wire down it and see what happens.
 

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Discussion Starter · #19 ·
Haha. Simple names are fine with me!

I'll do that tomorrow as well as order those parts.

I'll also post an update once the parts are in the car. Hopefully it won't take much more after this for the code to go away.

Thanks a lot for the help so far Rob. I'm sure you've saved me a couple hundred bucks already. :D
 

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Discussion Starter · #20 ·
Disaster!

I went to drive to class today and my car wouldn't start!

What happened?!

Everything electrical works; my wipers, hazards, and washing fluid worked, but they all went slower than normal.

I realized that when I was working on the EGR valve solenoid I didn't take off my negative battery cable like the Haynes manual says. Thinking this was the problem, I disconnected it and waited for a couple of minutes. When I reconnected it though, nothing changed.

Do I need a jump or did I do something completely disastrous?

Pleeeaaaase Help!
 
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